The present invention relates to stirrers for machines for making ice cream or the like.
The prior art includes many types of stirrer for ice cream-making machines, which adopt a variety of different mechanical principles. Generally speaking, the stirrer assemblies of such machines comprise a plurality of stirring means, which may be flat blades or helical blades, some also being capable of scraping the inside surface of the chilling chamber of the ice cream machine, and these are connected to a rotary drive shaft which in turn is connected to drive means. The connection between these blades and the shaft may be achieved in a variety of ways, for example by means of a frame, usually of metal, connected to said shaft and designed to support the stirring and scraping means as reported in EP-A-0497336.
However, such a construction would certainly be somewhat heavy, given the large quantity of metal parts; and besides this, the great number of parts of which the frame is made makes the structure complex, difficult to fit, service and clean, and therefore liable to present a health risk.
In the Italian Patent Application GE 92A000077 a stirrer is disclosed in which the helically-shaped blades are made of plastic and constitute the largest part of the stirrer, and said stirrer comprises a drive shaft, a plurality of radial screws mounted equidistantly on said shaft by means of one end, and a screw-connecting hub to which the screws are fixed at the opposite end from the shaft. This stirrer also has scraper means mounted on said screws.
Such a device has great advantages over the prior art; however, the scraper means are inserted onto the stirrer blades and have thrust means to ensure that they contact the inside surface of the chilling chamber. They are therefore still decidedly complicated in construction. Moreover, in this stirrer the fastening means are housed in holes formed in said screws, which are then stopped up with plastic inserts; this makes for a real risk from the hygiene point of view, quite apart from the obvious complications of construction.
It is an object of the present invention to provide a stirrer that combines the utmost mechanical simplicity with the utmost hygiene. In addition, another object of the invention is a stirrer that has scraper means formed in the simplest possible manner on said stirrer blades.
The subject of the present invention is therefore a stirrer for machines for making ice cream or the like, comprising:
a section of a rotary drive shaft; PA1 a first hub supporting a plurality of angularly equidistant radial spokes integral with the drive shaft section; PA1 a second hub supporting the same number of spokes as the first hub; PA1 which spokes of said second hub are provided at their ends with fastening components, and said first hub contains radial passages that extend, from a position diametrically opposite said spokes, axially through them, to accommodate pin-type fastening means; PA1 and a plurality of stirrer blades provided at their axial ends with holes having means for engaging said fastening means of said first and second hubs.
Advantageously, said stirrer blades are made of plastic.
A further subject of the present invention is the fact that said stirrer comprises scraper means formed integrally with the stirrer blades themselves, so that said blades have no additional holes, inserts or moving parts.
Another subject of the present invention is the method of assembling stirrers of the type described above, comprising the following steps: the stirrer blades are fastened to the ends of the radial spokes of the second hub; and the opposite ends of said blades are fastened to the first hub, which is integral with the drive shaft section, by inserting the fastening means into the radial passages inside said hub, said passages being sealed with suitable inserts.